DESCRIPTION
UCC5619 provides 27 lines of active termination for a SCSI (Small Computer Systems Interface) parallel bus. The SCSI standard recommends active termination at both ends of the cable.
The UCC5619 is ideal for high performance 5V SCSI systems. During disconnect the supply current is typically only 100µA, which makes the IC attractive for lower powered systems.
The UCC5619 is designed with a low channel capacitance of 2.5pF, which
eliminates effects on signal integrity from disconnected terminators at interim points on the bus.
The power amplifier output stage allows the UCC5619 to source full termination current and sink active negation current when all termination lines
are actively negated.
The UCC5619, as with all Unitrode terminators, is completely hot pluggable
and appears as high impedance at the teminating channels with V
TRMPWR
= 0V or open.
Internal circuit trimming is utilized, first to trim the 110Ω impedance, and
then most importantly, to trim the output current as close to the maximum
SCSI-3 specification as possible, which maximizes noise margin in fast
SCSI operation.
Other features include thermal shutdown and current limit. This device is
offered in low thermal resistance versions of the industry standard 36 pin
wide body QSSOP (MWP) and 48 pin LQFP (FQP).
Consult SSOP-36 (MWP QSSOP-36) and FQP-48 Packaging Diagram for
exact dimensions.
UCC5619
27-Line SCSI Terminator With Reverse Disconnect
BLOCK DIAGRAM
FEATURES
• Complies with SCSI, SCSI-2, SCSI-3,
SPI and FAST-20 (Ultra) Standards
• 2.5pF Channel Capacitance during
Disconnect
• 100µA Supply Current in Disconnect
Mode
• 4V To 7V Operation
• 110 Termination
• Completely Meets SCSI Hot Plugging
• –900mA Sourcing Current for
Termination
• +500mA Sinking Current for Active
Negation
• Logic Command Disconnects all
Termination Lines
• Trimmed Impedance to 5%
• Current Limit and Thermal Shutdown
Protection
10/98
UDG-96108
Circuit Design Patented
2
UCC5619
ABSOLUTE MAXIMUM RATINGS
TRMPWR Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +7V
Signal Line Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . 0V to +7V
Regulator Output Current. . . . . . . . . . . . . . . . . . . . . . . . . . 1.5A
Storage Temperature . . . . . . . . . . . . . . . . . . . −65°C to +150°C
Junction Temperature. . . . . . . . . . . . . . . . . . .−55°C to +150°C
Lead Temperature (Soldering, 10 Sec.). . . . . . . . . . . . . +300°C
Currents are positive into, negative out of the specified terminal. Consult Packaging Section of Databook for thermal limitations and considerations of packages.
LINE5
LINE6
LINE7
LINE22
LINE21
LINE19
LINE20
REG
LINE9
LINE8
GND*
LINE26
LINE27
LINE23
LINE24
LINE25
GND*
GND* GND*
36
35
34
33
32
31
30
29
28
27
1
2
3
4
5
6
7
8
9
10 GND*
11
12
13
14
15
26
25
24
23
22
16
17
18
21
20
19
LINE12
LINE11
LINE10
DISCNCT
LINE13
LINE14
LINE1
LINE2
LINE17
LINE18
TRMPWR
GND*
LINE16
LINE15
LINE4
LINE3
* MWP package pins 8 - 10 and 26 - 28 serve as heatsink/
ground.
QSSOP-36 (Top View)
MWP Package
48
47
46
45
1
44
43
424140
393837
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
192021
22
23
24
36
35
34
33
32
31
30
29
28
27
26
25
LINE 22
LINE 5
LINE 6
LINE 7
LINE 8
HS/GND
N/C
LINE 24
LINE 9
HS/GND
HS/GND
REG
LINE 19
LINE 20
LINE 21
TRMPWR
HS/GND
LINE 17
LINE 18
LINE 16
LINE 4
LINE 15
LINE 2
LINE 3
N/C
LINE 12
LINE 13
LINE 14
HS/GND
LINE 27
LINE 26
LINE 25
DISCNCT1
HS/GND
LINE 10
N/C
LINE 11
HS/GND
HS/GND
HS/GND
LINE 23
HS/GND
HS/GND
LINE 1
HS/GNDHS/GND
HS/GND
N/C
CONNECTION DIAGRAM
LFQP-48 (Top View)
FQP Package
ELECTRICAL CHARACTERISTICS Unless otherwise stated, these specifications apply for T
A
= 0°C to 70°C,
TRMPWR = 4.75V, DISCNCT = 4.75V, TA= TJ.
PARAMETER TEST CONDITIONS MIN TYP MAX UNITS
Supply Current Section
TRMPWR Supply Current All Termination Lines = Open 1 2 mA
All Termination Lines = 0.2V 630 650 mA
Power Down Mode DISCNCT
= 0V 100 200 µA
Output Section (Termination Lines)
Termination Impedance (Note 3) 104.5 110 115.5 Ω
Output High Voltage (Note 1) 2.6 2.8 3.0 V
Max Output Current V
LINE
= 0.2V, TJ= 25°C −22.1 −23.3 −24 mA
V
LINE
= 0.2V −20.7 −23.3 −24 mA
V
LINE
= 0.2V, TRMPWR = 4V, TJ= 25°C (Note 1) −21 −23 −24 mA
V
LINE
= 0.2V, TRMPWR = 4V (Note 1) −20 −23 −24 mA
3
UCC5619
PIN DESCRIPTIONS
DISCNCT: Taking this pin low causes all channels to
become high impedance, and the chip to go into
low-power mode; a high state or leaving it open allows
the channels to provide normal termination.
GND: Ground reference for the IC.
LINE1 - LINE27: 110Ω termination channels.
REG: Output of the internal 2.7V regulator; bypass with a
4.7 F capacitor to GND.
TRMPWR: Power for the IC; bypass with a 4.7 F
capacitor to GND.
ELECTRICAL CHARACTERISTICS Unless otherwise stated, these specifications apply for T
A
= 0°C to 70°C,
TRMPWR = 4.75V, DISCNCT = 4.75V, TA= TJ.
PARAMETER TEST CONDITIONS MIN TYP MAX UNITS
Output Section (CONT.)
V
LINE
= 0.5V 22.4 mA
Output Leakage DISCNCT = 0V, TRMPWR = 0V to 5.25V 10 400 nA
Output Capacitance DISCNCT
= 0V (Note 2) 2.5 4 pF
Regulator Section
Regulator Output Voltage 2.6 2.8 3.0 V
Drop Out Voltage All Termination Lines = 0.2V 0.4 0.8 V
Short Circuit Current V
REG
= 0V −650 −900 –1300 mA
Sinking Current Capability V
REG
= 3.5V 300 500 900 mA
Thermal Shutdown 170 °C
Thermal Shutdown Hysteresis 10 °C
Disconnect Section
Disconnect Threshold 0.8 1.5 2.0 V
Input Current DISCNCT
= 0V –20 –60 µA
11
29
25TERMPWRDISCNCT
DATA BYTES
1AND2
+2 PARITY BITS
7
REG
4.7µF
4.7µF
TO SCSI BUS
TERMPWR
17
LINE1 LINE27
CONTROL
BYTES
TO DRIVERS
AND
RECEIVERS
UCC5619
Figure 1. Typical wide SCSI bus configuration using the UCC5619
UDG-98072
UNITRODE CORPORATION
7 CONTINENTALBLVD. • MERRIMACK, NH 03054
TEL. (603) 424-2410 FAX (603) 424-3460
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